But is it a case of "air today and gone tomorrow" or is
this a system which could spell the end of the petrol engine and reduce
global warming into the bargain?

That's the question which could be answered later this month
when the MDI Aircar is launched in the capital - it is already a reality
in France where it has been tootling about since 1998.

Designed by a Frenchman, Guy Negre, the car is being developed by
Spanish firm MDI and there is massive interest being shown by several
countries including China and Mexico.

Running on compressed air, its engine features no combustion
chambers and therefore produces no pollutants whatsoever. In fact, the
air expelled from the engine is cleaner than the air that goes in, says
its makers.

It will be on show to the public on September 20 before its
imminent arrival on the market.

The fuelless, emission-free vehicle is also aimed at offering
entrepreneurs and institutions the chance to take part in
establishingfactories in the UK.

The MDI (Moteur Development International) has a claimed top speed
of 68 mph and a range of 124 miles on a tank of air - considerably more
than most electric vehicles available today.

When recharging the compressed air tank, the car needs to be
connected to the electric mains for three to four hours or attached to
an air pump in a petrol station for only two minutes.

MDI claims the car's maintenance cost is 10 times less than
that of a petrol-powered car, costing pounds 1 for the car to travel for
up to eight hours or to cover 124 miles in a built-up area.

So how does it work?

Up to 90 cubic metres of compressed air is stored in fibre tanks.
The expansion of this air pushes the pistons and creates movement. The
atmospheric temperature is used to reheat the engine and increase the
road coverage. The air conditioning system makes use of the expelled
cold air. Due to the absence of combustion and the fact there is no
pollution, an oil change is only necessary every 31,000 miles.

Four models have been made: a car, a taxi, a pick-up truck and a
van.

The final selling price will be approximately pounds 5,500.

MDI was founded in Luxembourg, is based in the south of France and
has its commercial office in Barcelona. It has developed the car over
the past 10 years and the technology is protected by more than 30
international patents.

MDI says its expansion has just begun and it is offering 20
licences in the UK as manufacturing areas for cars as well as offering
other licences in the nautical and public transport sectors.